1. Field of the Invention
The present invention relates to optical fiber technology. More specifically, the present invention relates to techniques for splicing optical fiber.
While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.
2. Description of the Related Art
At present, only a few optical fiber manufacturers have the capability of making long, high strength, low loss, high quality fibers. Accordingly, optical fiber splicing is required more and more frequently to meet certain demanding applications.
High strength, low loss optical fiber splicing requires: (1) proper fiber preparation, (2) proper fiber alignment prior to fusion, (3) the bringing together and mating of the fibers during the fusion process, and (4) application of a precise temperature profile during the fusion and post fusion annealing processes.
Control of the temperature profile is of particular importance. The temperature profile is the timing of the application of specific amounts of thermal energy for controlled durations. Fiber splicing with inadequate control of the temperature profile may result in thermal shock, i.e., structural damage to the fiber.
Conventional fiber splicing techniques include hydrogen/oxygen flame torching, H-Cl gas flame splicing, and electric arc fusing. Hydrogen/oxygen flame torching was not an automated process. The temperature of the fiber had to be controlled by the operator. Splice quality was inconsistent due to the dependence on the skill of the operator. It was also difficult to align and control the movement of the fibers with the precision necessary to achieve a low loss splice. Hence, hydrogen/oxygen flame torching suffered low yields of high strength, low loss, high quality optical fiber due to poor control of the temperature profile, alignment and movement of the fiber.
H-CI gas flame splicing was known to yield high strength splices, but H-CI gas was found to be extremely hazardous.
Electric arc fusing is an automated process by which a computer controlled fiber positioner aligns the fiber ends face-to-face until optimum transmission is achieved through the junction. A high voltage is applied to two electrodes creating electric art induced heat. With an appropriate temperature profile, the temperature of the fiber reaches the melting point of glass, surface tension pulls the fiber ends together and the ends are fused. With insufficient heat, the glass will not melt. With excessive heat, the fiber ends melt away from each other.
While effective in providing a high strength splice, electric arc fusing has certain shortcomings. First, as with torch and flame splicing, it is somewhat difficult to control the temperature profile with this technique. Secondly, the ionized air gases generated by the electrode, tend to contaminate the fusion surfaces. As a result of the above problems this technique tends to yield inconsistent results.
Thus, there is a need in the art for an optical fiber splicing system which affords better control of the splicing temperature without contamination. In addition, there is a need for a system which would apply fusion heat without disturbing the alignment of the fiber ends and without causing thermal shock to the fiber. Further, there is a need for a system which would provide consistent high strength, low optical loss fusion splicing.